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    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        var a = 1;
        var b = 2;
        var temp;
        temp = a;
        a = b;
        b = temp;
        console.log('a的值'+a,'b的值'+b);

        var c = 12;
        var d = 13;
        c = c + d;
        d = c - d;
        c = c - d;
        console.log('c的值'+ c,"d的值"+ d);
    </script>
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